This invention relates to a mixing head for mixing more than two fluid components, especially for the form foaming of polyurethanes, having a mixing chamber supplied by nozzles for the components and a return flow system for recirculating the components at the end of a mixing cycle.
In a known mixing head of this type as disclosed in DTOS No. 24 16 686 two tappet valves are slidably mounted in a housing. Supply lines for the components are connected to an axial bore of each tappet valve through radial bores. Each tappet valve is also provided with a longitudinally displaced radial bore which opens into a common mixing chamber inside the housing. A cleaning rod is axially movable in the mixing chamber. This rod is utilized to press or expell the mixed components out of the chamber, for example into a mold form. At the end of a mixing cycle the nozzles in the tappet valve are moved into connection with a return line, so that the components can be delivered back to their containers in a recirculating manner. This mixing head is primarily intended for the simultaneous working of just two fluid components.